Reduced active protection to the cochlea during physical exercise.

The present investigation was designed to evaluate whether dynamic physical exercise is able to modify stapedius reflex (SR) activity and, as a consequence, to influence the amount of temporary threshold shift (TTS). Experimental subjects were 10 normal-hearing male volunteers, aged 27-34 years (mean 30.8). SR parameters in the time-domain were assessed before, during and after submaximal exercise test, performed for 10 min on an ergometer cycle at 50% of maximum work capacity. The same parameters were also investigated in the absence of exercise, at time-matched intervals. In addition, the combined effect of noise and exercise was studied. The outcome of the investigation indicates that dynamic physical exercise depresses the SR and potentiates noise-induced TTS. The mechanisms underlying the present findings are discussed.